by Adam Silver
Senior Product Manager
Adaptec Inc., Milpitas, CA
Tell the truth, now. In your years of experience with video and with computers, haven't you at some time had the thought: "Why don't these damn things work together?" Of course you have. If you were bold enough to actually voice this thought, friends and colleagues no doubt put an instant end to the reverie. "Hey, they simply don't connect! One's digital, the other isn't. So forget it." or words to that effect.
But change is in the air. Video and computers, once radically different technologies, have been on convergent paths for years. While the first PCs only processed text, today's models process sound, graphics, animation, and -- at a limited frame-rate and window-size -- full-motion video.
Could you add hardware to a system to upgrade its video capabilities for editing? Absolutely. But, at least for now, prepare to shell out the price of a compact car to get there.
Don't despair. Two new "standards" have recently emerged that will make all this processing power a reality at a far more acceptable price. The first, called IEEE 1394, has come out of the computer industry. The second, DVC, emerges from the world of video.
1394: Not the Year Columbus Hit The New World
Typically, computers transfer data through channels called "busses." Virtually all of these deal with data in a parallel manner: 8, 16 or 32 bits of data, moving along parallel lines from a computer to a peripheral. But video data is sent serially, one bit leading another, in a line.
The initial implementation of 1394 for computer applications was developed by Apple Computer and is called "FireWire." (It's important to understand that while FireWire is the first implementation, it is not the actual standard. And Apple licenses it. It is, however, the only one currently available.)
So here's the good news about buses based on 1394.
DVC: Not A Rock Group
DVC is a new video-compression and videotape format that is quickly becoming a global standard. Over 55 companies (including the major camcorder manufacturers -- Matsushita, Philips, Sony and Thomson) have endorsed DVC. DVC is unique in that it brings digital down into the camcorder, which, until now, has not been possible. For the most part, high-quality digital video has meant expensive camcorders and expensive editing systems. Make that "very expensive."
Sony's DVC-based consumer camcorders are available now and other manufacturers will soon be shipping. (See the Digital Video features in the December 1995 issue of Camcorder - Editor.) (They offer the FireWire for connecting to computers or other camcorders as an option.) As mentioned, the most significant aspect of DVC is that the video information stored on the tape is digital: ones and zeros.
Much of the video we watch today on television has been digitized at some point in the production process. When video is digital it can be manipulated in the same way that we manipulate data on a PC (like cut, copy and paste, plus the ability to add special effects). These processes are done without any loss of quality. A DVC camcorder digitizes the video image that is being shot, compresses it and writes it to the video cassette.
This DVC minicassette is much smaller than existing videocassettes, fitting neatly in the palm of your hand.
From a digital video-editing perspective, the best part about the new Sony DVC camcorders is that they both include a 1394 connector, subtly labeled "DV In/Out," with an optional FireWire. So now there are products shipping today which combine both DVC and 1394.
Editing Digital Video Today
In order to edit digital video on a computer at the present time, you would use a video-digitizing and - compression card (often referred to as a video-capture card). This card includes the ability to digitize (decode) the incoming analog video, compress it and write it to the hard disk. Using a digital video-editing program like Adobe Premiere, you can begin editing. When you have finished editing you must get the final video clip out of the computer and then convert (encode) it back to analog video.
The silicon chips required for digitizing, compression and encoding are expensive and usually require onboard memory chips, which add to the cost. A significant challenge for video-capture card vendors has been ensuring that during digitization and compression, the audio and video signals remain synchronized; this is critical for correct lip sync. Some vendors include audio-digitizing and -synchronizing chips on their cards to address this problem. However, these chips also add to the cost of the card. A typical video-capture card that supports full-screen, full-motion video will cost more than $1,000, and a fully equipped system costs well in excess of $15,000.
Editing Digital Video With Future 1394/DVC Systems
A DVC camcorder manages the digitization, compression and audio-synchronization processes during shooting, so all of the sophisticated and expensive components found on current capture cards are no longer needed; in fact, the entire philosophy of digitizing and compressing video using a capture card changes completely. The video and audio information on a DVC videocassette is already digital, so all that is required is a means of copying the information onto the computer's hard disk. The video can be edited once it's on the hard disk and, when the edits are complete, the new clip can be copied back to videotape.
This could be achieved using a straightforward interface card with a 1394 connector on the back of it. These types of products are expected to be available in 1996, and should cost significantly less than the systems available today.
What Types of Systems Can You Expect?
The initial systems shipped are likely to rely on a connection to a SCSI hard disk. SCSI disk drives are fast, high quality and provide the highest storage capacity available today.
Transferring a DVC stream coming into the PC over 1394 to a SCSI hard disk will require serial-to-parallel conversion. This should be relatively easy given that the data is digital.
Who Will the Users Be?
The first users of PC-based 1394/DVC editing solutions are likely to be event videographers and small video-production houses. People in this sector of the market should have the money to invest in the camcorders (currently in the $2,700- to - $4,200 price range) and the necessary disk storage required to put a system together. DVC runs at 3.5 megabytes per second. So, in order to edit 60 minutes of video, you would need 12.6 gigabytes of hard-disk storage.
With the declining cost of camcorders and hard drives, these types of systems will be available to broader markets, including video enthusiasts and home users in the not-so-distant future.
Be sure to Register to receive future updates and information from Adaptec. Or, you can always contact us via email at: 1394@corp.adaptec.com with any questions.
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